PHYLUM COELENTERATA(CNIDARIANS)Pages 323- 325

3 CLASSES OF COELENTERATESHydrozoa Hydra

Scyphozoa Jellyfish Man of War

Anthozoa Corals Sea Anemone

Page 323 Figure 9

PHYSICAL CHARACTERISTICS1. Where do they live? All live in water most in salt water but the hydra lives in fresh water2. Symmetry radial (see page 316)Body Structure is more complex than a sponge (therefore they can eat larger animals)

4. Cellular Structure like a sac with one opening mouth-like structure where food enters and leaves (not like the sponge)2 cell layers : ectoderm protects and covers outside endoderm inner layer that lines the sac-like digestive cavity ***they have specialized cells**organized tissues muscle tissue and a nerve net Why? Refer to page 323 Central cavity with only 1 opening called the gastrovascular cavity - this is the opening (mouth) where food enters and leavesAll have tentacles with nematocysts tentacles arm like projections surrounding the mouth nematocyst stinging cells on the tentacles which shoot poisonous threads or darts

Body FormsPolyp diagram page 324See overhead diagram

Medusa diagram page 324See overhead diagram

LOCOMOTIONStays in place attached to rock examples: sea anemone and coralMedusa example: jellyfish move around swim by pumping water in and out of digestive cavity called jet propulsion pumping water in and out of cavityPolyp example: hydra crawls See diagram

FOOD GETTING*captures food with nematocysts by paralyzing small animals that swim into tentaclesNematocyst fire poison dartsParalyzes preyTentacles bring food to mouth

REPRODUCTIONSexually sperm and egg **separate sexesAsexually Budding example: Hydra Regeneration

*Phylum Cnidaria

*Phylum Cnidaria Radial symmetryMouth at oral end surrounded by tentacles. One opening into and out of gastrovascular cavity.Cnidocytes that discharge pneumatocystsTwo body formsPolypMedusaTwo germ layersNerve net

*Radial symmetry

*Mouth and Tentacles

*Fig. 13.2

*Generalized Cnidarian Life CycleCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

*Cnidocyte Structure and Nematocyst DischargeCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

*Diploblastic - 2 germ layers

Epidermis - outer covering (ectoderm)Mesoglea - middle non-living jelly-like layerGastrodermis - lines gastrovascular cavity (endoderm)

*Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Cnidarian Body Wall

*Nervous SystemNerve cells, arranged in a nerve net.

*Class HydrozoaFreshwater & marine.Cnidocytes present only on epidermis.Medusa (if present) with a muscular velum.Mesoglea without ameboid cells.Asexual reproduction by budding.Sexual reproduction via gametes produced by epidermis & released into water.

*Class HydrozoaHydraObeliaGonionemusPhysalia

*Class HydrozoaHydraSpermariesOvariesEncapsulatedembryoSexual cycleAsexual cycleBudding

*GastrovascularcavityEpidermisMesogleaGastrodermis

HydraBody Wall

*Fig. 13.9

*Obelia

*ObeliaMedusaeGonangiumMedusa bud

*Class Hydrozoa Gonionemus

*Class HydrozoaGonionemus

*Class HydrozoaPhysalia

*Class Scyphozoa

Tentacles up to 70 meters in lengthCnidocytes present in gastrodermis & epidermisThick mesoglea contains ameboid cellsGametes produced by gastrodermisAll marine

*Class ScyphozoaAurelia

*Aurelia Life HistoryCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

*Fig. 13.18

*Planula LarvaCiliated larva than can swim to a new location

*AureliaEggsMesogleaGastrovascularcavityMouth

*Aurelia

*Class CubozoaMedusa dominant & cuboid Tentacles arise at four corners from blade-like pendalium.All marineStrong swimmers which prey primarily on fishStings of some may be fatal within minutes to humans.

*Class CubozoaGonadTentaclePedalium

*Class CubozoaChironex Sea Wasp

*Class AnthozoaMedusa stage absentSolitary or colonialSome produce protective skeletonsGastrovascular cavity subdivided by at least 8 mesenteriesCnidocytes on mesenteriesMesoglea contains ameboid cellsAll Marine

*Class AnthozoaSea Anemone

*Class AnthrozoaMetridiumMouthTentaclesPharynxSeptumGastrovascular cavity

*Symbiosis

*Class AnthozoaCoralsProtective skeleton of calcium carbonatePolyp retracts when not feeding

*ZooxanthellaePhotosynthetic dinoflagellates (brown)Live in coralsProvide nutrients for coral by photosynthesisMutualism

*CoralsColony of interconnected polyps

*Class AnothozoaMeandrinaBrain Coral

*Class AnothozoaGorgoniaSea Fan

*Class AnothozoaTubiporaPipe Organ Coral

*Class AnothozoaActinodiscusMushroom Coral

*Class AnothozoaAcroporaStaghorn Coral

*Coral ReefsFormed over thousands of years from successive layers of coral skeleton deposits (calcium carbonate forms underwater mountains of coral animal skeletons)The underwater equivalent of the amazon jungle- very high species diversity and biomassReefs contain sponges, colonial hydrozoans, anemones, many varieties of coral, fish, many types of worms weve not discussed, not to mention bryozoans, ctenophores, protists, bacteria, etc etc..

*Coral Reef EcosystemCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Photo McGraw-Hill Higher Education, Barry Barker, Photographer

*AnthozoaScyphozoaCubozoaHydrozoaCladogram of Cnidaria

*The End

**Fig. 13.2***Fig. 13.9*Fig. 13.12b*Fig. 13.18****

*